This invention relates to a method and apparatus for displaying an image or the like on a display screen, and more particularly to a method and apparatus for simultaneously displaying an enlargement target region and its enlarged equivalent on the same display screen.
It has been demanded to provide a method for enlarging part of a map or the like displayed on a display screen. In an attempt to meet the above demand, a method for separately displaying an enlarged map only on a display screen is proposed in, for example, JP-A-62-153889. The disclosure of the cited application will be described with reference to FIGS. 2A and 2B. FIG. 2A shows an entire original road map 1 including a target region 2 to be enlarged on a display screen. After enlargement of the target region 2, the entire original road map 1 including the target region 2 is erased on the display screen to be replaced by an enlarged map 3 of the target region 2. FIG. 2B shows that the enlarged map 3 only of roads in the target region 2 is displayed on the display screen.
However, according to the proposed method, of JP-A-62-153889 the positional relation of the enlarged road map 3 of the target region 2 in the entire original road map 1 cannot be accurately recognized.
FIGS. 3A and 3B show application of the proposed method of JP-A-62-153899 for an enlarged display of a contour map. FIG. 3A shows an original contour map 1, and FIG. 3B shows an enlarged contour map 3 of a target region 2. However, with the enlarged contour map 3 only, it is impossible to accurately identify the details of linkage among the contour lines.
JP-A-62-35983 proposes a method for displaying both an enlarged pattern and its original pattern on the same display screen as shown in FIGS. 4A and 4B. FIG. 4A shows that a point located at the upper left corner of a target region 2 to be enlarged is externally specified thereby setting the target region 2 to be enlarged. This target region 2 is shown by a dotted square in FIG. 4A. Then, a point located at the upper left corner of an enlarged pattern display region and an enlargement ratio are specified so as to set the enlarged pattern display region. FIG. 4B shows both the enlarged pattern 3 and its original pattern 2. A raster scanning method is used to display the enlarged pattern 3. The manner of raster scanning is such that, as soon as scanning of the enlarged pattern display region is to take place, the data reading system is switched for reading data of the enlargement target region 2, and the scanning speed is changed from the standard speed to that used for enlargement.
The related art method disclosed in JP-A-62-153889 cited above has such problems to be solved from the aspect of ease of visibility that, because no consideration is taken for displaying an enlarged map of a target region in relation to the target region, the positional relation of the enlarged target region in the entire original map as well as the configuration of the enlarged map cannot be accurately recognized.
Also, in the case of the method disclosed in JP-A-62-35983 cited above in which an original pattern and its enlarged pattern are simultaneously displayed on the same display screen, the enlargement ratio and the position of displaying the enlarged pattern must be externally specified. Thus, this related art method has such problems to be solved from the aspect of manipulatibility that the enlarged pattern tends to become extremely small depending on the enlargement ratio, or, in a contrary case, the enlarged pattern tends to become extremely larger than the whole area of the display screen, and the enlargement ratio must be re-set.
With a view to solve the problems pointed out above, it is an object of the present invention to provide a method and apparatus of the type for simultaneously displaying both a target region to be enlarged in an entire original image and its enlarged image on the same display screen, in which the enlarged image to be displayed is automatically disposed on the display screen.
Another object of the present invention is to provide a method and apparatus of the type described above in which the enlargement target region and its enlarged image are readily visibly disposed and displayed on the same display screen so that the enlarged image can be readily accurately recognized.
Still another object of the present invention is to provide a method and apparatus of the type described above in which, while shifting the enlargement target region along a linear or the like on the display screen, its enlarged image is automatically disposed and displayed on the same display screen at the same time, so that the method and apparatus can be effectively utilized for the purpose of navigation.
Other objects of the present invention will become apparent from the following detailed description made in conjunction with the accompanying drawings.
An embodiment of the image displaying apparatus of the present invention comprises displaying means for displaying an enlarged image of part of an entire original image including characters, patterns, etc. in a relation superposed on the entire original image, input means for pointing to specify an enlargement target in the entire original image, and automatic disposing means for preferentially specifying computing the values of the area of the enlargement target region, the area of the enlarged image display region and the enlargement ratio, so that one of these values becomes equal to a predetermined one or a maximum, and disposing the enlargement target region and the enlarged image display region so as to be readily distinguished from each other on the display screen.
Further, in order that the enlarged image is readily visible, the enlargement target region and the enlarged image display region are disposed and displayed on the display screen so that a peripheral region adjoining the enlargement target region is disposed between the enlargement target region and the enlarged image display region.
According to the apparatus of the present invention constructed as described above, an enlargement target region including a specified target to be enlarged and an enlarged image of the target are automatically disposed on the same display screen so as to be readily distinguished from each other. That is, when a point on the display screen is pointed to specify an enlargement target region, a minimum region having a minimum or nearly minimum area that can be recognized on the display screen provides the enlargement target region. Usually, a basic region which is n times (n: a predetermined integer) as large as the minimum region is automatically set. Then, an expected enlarged image display region having a greatest margin is selected on the display screen in relation to the basic region, and the enlarged image is displayed on the selected expected display region. The purpose of preferential specifying in this case is that the enlarged image display region has a maximum or nearly maximum area. The terms xe2x80x9cmaximumxe2x80x9d and xe2x80x9cminimumxe2x80x9d are used in the specification of the present application to designate not only the maximum and minimum values but also practical values close to them.
Further, when the area of the enlargement target region is to be maximized, the enlargement ratio is selected to be a minimum, and, under the condition where the length of the line connecting the center of the basic region and the expected enlarged image display region is kept constant, the areas of these two regions are re-computed. On the other hand, when the enlargement ratio is to be maximized, the area of the enlargement target region is limited to that of the minimum region described above.
Thus, by preferentially specifying the priority of one of the area of the two regions and the value of the enlargement ratio over the others, thereby correspondingly changing the other values, the enlarged image, which is readily visible and has a high degree of flexibility, can be automatically disposed and displayed on the display screen.
When fixation of the areas of the two regions and the value of the enlargement ratio at predetermined or specific values cannot attain the required condition, the entire original image including the enlargement target region is automatically scrolled on the display screen, and the regions are then automatically disposed on the display screen.
In order that the enlargement target region and the enlarged image can be clearly distinguished from each other, a space is provided at the boundary between these two regions and a peripheral region adjoining the enlargement target region is displayed in this space. By displaying the peripheral region, the contents of the enlargement target region and the enlarged image can be readily compared with and clearly distinguished from each other not only when the enlargement target region and the enlarged image are disposed in a non-overlapping relation but also when they may overlap each other.
According to the present invention, the enlarged image can be automatically disposed in a location outside an erase-inhibited region of the entire original image.
According to the present invention, the enlargement target region can be specified by not only pointing to the minimum region on the display screen but also pointing to a line (a linear pattern) on the display screen. That is, while shifting the enlargement target region along the line, the corresponding enlarged image can be continuously and automatically disposed on the display screen.
Also, according to the present invention, besides directly specifying the enlargement target region by pointing on the display screen, the enlargement target region can be specified by retrieval of display data or associated data by means of, for example, a key word input.
Also, according to the present invention, the enlarged image displayed on the enlarged image display region represents not only the enlarged detail itself of the enlargement target region but also-information related to the target region, for example, a sectional figure, an illustrational on explanatory figure or attribute information.